Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 414 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we keep it the same (c) we measure it
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the iron setting (c) the kind of juice (d) the same paper
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) white paper (d) a balloon
5. 5.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) the same paper (c) how dark the writing is (d) the ironing time
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
9. 9.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
12. 12.🔍 Which is the odd one out? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) reading the message
13. 13.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
14. 14.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) turmeric powder (d) a small bowl
16. 16.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) ironing the paper (d) putting the iron away
17. 17.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
18. 18.True or false: ironing the paper is a job a child can do. (a) True (b) False
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
20. 20.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) white paper (c) lemon juice (d) an adult with an iron
22. 22.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) plugging in the iron
23. 23.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) yeast (d) a cotton bud
26. 26.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) an adult with an iron (c) white paper (d) lemon juice
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a mirror (c) white paper (d) an adult with an iron
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
30. 30.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
32. 32.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
33. 33.True or false: yeast is needed for the secret lemon message. (a) True (b) False
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
36. 36.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
37. 37.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) ironing the paper
38. 38.True or false: writing the message is a job a child can do. (a) False (b) True
39. 39.True or false: white paper is needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) white paper (d) a mirror

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids