Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 974 · 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 can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) it turned into air (d) the ink is magnetic
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
3. 3.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) yeast (d) a magnet
4. 4.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) a battery cell (d) a mirror
5. 5.True or false: ironing the paper is a job a child can do. (a) False (b) True
6. 6.True or false: putting the iron away is a job a child can do. (a) True (b) False
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.True or false: cutting the lemon is a job for an adult. (a) False (b) True
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a battery cell (d) a cotton bud
10. 10.⚖️ 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 same paper (c) how dark the writing is
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
14. 14.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
15. 15.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a mirror (d) a small bowl
16. 16.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) yeast (c) a mirror (d) a balloon
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) paper turns lemony (d) heat adds colour
18. 18.True or false: yeast is needed for the secret lemon message. (a) True (b) False
19. 19.True or false: reading the message is a job a child can do. (a) True (b) False
20. 20.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) reading the message
21. 21.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) dipping the cotton bud (d) reading the message
22. 22.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
23. 23.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
24. 24.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
25. 25.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) yes, if shaken (d) no, it stays brown
26. 26.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) a balloon (d) a cotton bud
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) turmeric powder
29. 29.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it can burn skin (d) it is cold
30. 30.⚖️ 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
31. 31.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
32. 32.🧺 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) a balloon (d) a cotton bud
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a cotton bud (d) yeast
34. 34.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
35. 35.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a magnet (c) lemon juice (d) a small bowl
37. 37.⚖️ 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 kind of juice (c) the same paper (d) how dark the writing is
38. 38.True or false: plugging in the iron is a job for an adult. (a) False (b) True
39. 39.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
40. 40.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) dipping the cotton bud (d) plugging in the iron

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