Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 932 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) white paper (c) an adult with an iron (d) a small bowl
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
3. 3.True or false: ironing the paper is a job a child can do. (a) False (b) True
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a balloon (d) a cotton bud
6. 6.True or false: white paper is needed for the secret lemon message. (a) False (b) True
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the ironing time (d) the kind of juice
8. 8.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) a small bowl (d) white paper
10. 10.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) an adult with an iron (c) a magnet (d) a balloon
11. 11.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
12. 12.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
13. 13.⚖️ 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
14. 14.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) reading the message
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
16. 16.True or false: writing the message is a job a child can do. (a) True (b) False
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) an adult with an iron (d) lemon juice
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) a battery cell (d) a balloon
19. 19.True or false: plugging in the iron is a job a child can do. (a) False (b) True
20. 20.True or false: plugging in the iron is a job for an adult. (a) True (b) False
21. 21.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
22. 22.⚖️ 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 keep it the same (c) we measure it
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) a cotton bud (d) a small bowl
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) dry juice is see-through (c) the paper ate it (d) it turned into air
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) wash your hands (d) skip washing
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) white paper (d) yeast
28. 28.⚖️ 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
29. 29.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) putting the iron away (d) letting the paper dry
30. 30.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
31. 31.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) putting the iron away
33. 33.True or false: letting the paper dry is a job a child can do. (a) False (b) True
34. 34.⚖️ 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
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) reading the message
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a small bowl (d) a magnet
37. 37.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
38. 38.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
39. 39.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
40. 40.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) dipping the cotton bud (d) letting the paper dry

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