Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 48 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
3. 3.⚖️ 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 change it (c) we measure it
4. 4.🛟 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
5. 5.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
6. 6.True or false: cutting the lemon is a job a child can do. (a) False (b) True
7. 7.⚖️ 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
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
9. 9.True or false: ironing the paper is a job a child can do. (a) False (b) True
10. 10.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) reading the message
11. 11.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
12. 12.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
13. 13.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
15. 15.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) whoever is fastest (d) any child
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a magnet
17. 17.True or false: white paper is needed for the secret lemon message. (a) False (b) True
18. 18.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ 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 ironing time (c) the kind of juice (d) the same paper
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same cotton bud (c) the iron setting (d) how dark the writing is
21. 21.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) white paper (c) a magnet (d) a battery cell
23. 23.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
24. 24.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) letting the paper dry (d) writing the message
25. 25.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
28. 28.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
29. 29.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) cutting the lemon (d) putting the iron away
30. 30.True or false: plugging in the iron is a job a child can do. (a) True (b) False
31. 31.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
33. 33.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) letting the paper dry
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
35. 35.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) letting the paper dry (d) ironing the paper
36. 36.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
37. 37.⚖️ 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
38. 38.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
39. 39.True or false: writing the message is a job for an adult. (a) True (b) False
40. 40.True or false: plugging in the iron is a job for an adult. (a) False (b) True

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