Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 423 · 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.True or false: cutting the lemon is a job for an adult. (a) True (b) False
2. 2.⚖️ 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
3. 3.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) writing the message (d) putting the iron away
4. 4.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) no, it stays brown (d) yes, if cooled
5. 5.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) it gets darker (c) the paper floats (d) writing turns green
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) yeast (d) a balloon
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) lemon juice (d) a balloon
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the ink is magnetic (d) the paper ate it
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a battery cell (d) a magnet
11. 11.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a small bowl (d) an adult with an iron
12. 12.⚖️ 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 kind of juice (c) the iron setting (d) the ironing time
13. 13.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) ironing the paper
14. 14.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) writing the message (d) letting the paper dry
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a mirror (d) a cotton bud
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
18. 18.⚖️ 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) True (b) False
19. 19.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
20. 20.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
21. 21.🍋 Which of these steps is a job a child can do? (a) writing the message (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
23. 23.⚖️ 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
24. 24.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
26. 26.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) yeast (c) a balloon (d) a mirror
27. 27.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) heat adds colour (d) paper turns lemony
28. 28.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
30. 30.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) ironing the paper (d) cutting the lemon
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
32. 32.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) magnetic (d) musical
33. 33.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
34. 34.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
35. 35.⚖️ 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 keep it the same (c) we measure it
36. 36.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
37. 37.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
38. 38.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
39. 39.True or false: letting the paper dry is a job a child can do. (a) False (b) True
40. 40.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False

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