Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 404 · 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: a battery cell is not needed for the secret lemon message. (a) False (b) True
2. 2.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
3. 3.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) a cotton bud (d) an adult with an iron
5. 5.⚖️ 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
6. 6.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
7. 7.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) ironing the paper
8. 8.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a balloon (d) a small bowl
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) how dark the writing is (c) the same cotton bud
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a magnet
13. 13.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is sticky (d) it is magnetic
14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
16. 16.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) writing stays faint (d) it gets darker
17. 17.⚖️ 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
18. 18.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
19. 19.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a small bowl (d) a magnet
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) an adult with an iron (d) a cotton bud
22. 22.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
23. 23.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
24. 24.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is (d) the ironing time
26. 26.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) yeast (d) white paper
27. 27.True or false: reading the message is a job for an adult. (a) False (b) True
28. 28.⚖️ 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
29. 29.⚖️ 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
30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
31. 31.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
33. 33.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) an adult with an iron (d) yeast
35. 35.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
36. 36.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
37. 37.⚖️ 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
38. 38.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) white paper
40. 40.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True

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