Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 213 · 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.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
2. 2.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) reading the message (d) letting the paper dry
3. 3.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
4. 4.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
5. 5.True or false: putting the iron away is a job a child can do. (a) True (b) False
6. 6.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a battery cell (d) a magnet
7. 7.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) reading the message
8. 8.True or false: yeast is needed for the secret lemon message. (a) False (b) True
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) turmeric powder (d) a battery cell
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
11. 11.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
12. 12.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
14. 14.True or false: letting the paper dry is a job for an adult. (a) True (b) False
15. 15.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
16. 16.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) ironing the paper (d) writing the message
17. 17.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
18. 18.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) writing the message (d) plugging in the iron
19. 19.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
20. 20.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
23. 23.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) ironing the paper
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a battery cell (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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
29. 29.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) putting the iron away
30. 30.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) ironing the paper
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
32. 32.True or false: white paper is needed for the secret lemon message. (a) False (b) True
33. 33.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
34. 34.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) putting the iron away
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a battery cell (d) a cotton bud
36. 36.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
37. 37.True or false: plugging in the iron is a job for an adult. (a) False (b) True
38. 38.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same

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