Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 131 · 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.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
2. 2.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) dipping the cotton bud (d) letting the paper dry
3. 3.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) turmeric powder (d) white paper
5. 5.True or false: white paper is needed for the secret lemon message. (a) False (b) True
6. 6.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
7. 7.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
8. 8.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
9. 9.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) white paper (d) lemon juice
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) how dark the writing is (d) the same paper
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
16. 16.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
17. 17.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) reading the message
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
19. 19.True or false: cutting the lemon is a job a child can do. (a) False (b) True
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) an adult with an iron (d) a mirror
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a cotton bud
22. 22.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
23. 23.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) reading the message (d) putting the iron away
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) the iron setting (d) how dark the writing is
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a mirror (d) a cotton bud
26. 26.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
27. 27.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
29. 29.True or false: ironing the paper is a job a child can do. (a) False (b) True
30. 30.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a mirror (c) white paper (d) a balloon
32. 32.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
33. 33.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
34. 34.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) a small bowl (d) a balloon
35. 35.True or false: letting the paper dry is a job for an adult. (a) False (b) True
36. 36.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) writing the message
37. 37.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
39. 39.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) lemon juice (d) yeast

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