Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 315 · 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.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
3. 3.True or false: letting the paper dry is a job a child can do. (a) False (b) True
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a mirror (d) a small bowl
5. 5.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
6. 6.True or false: cutting the lemon is a job for an adult. (a) False (b) True
7. 7.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) plugging in the iron (d) putting the iron away
8. 8.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a mirror (d) turmeric powder
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the iron setting (d) the ironing time
10. 10.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
11. 11.True or false: cutting the lemon is a job a child can do. (a) False (b) True
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) white paper (d) an adult with an iron
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) white paper (d) a mirror
14. 14.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) a balloon (d) a mirror
15. 15.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
16. 16.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
17. 17.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a battery cell (d) a balloon
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) white paper (d) a magnet
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) lemon juice (d) a small bowl
22. 22.True or false: putting the iron away is a job for an adult. (a) True (b) False
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) yeast (c) a cotton bud (d) white paper
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) skip washing (d) lick your fingers
26. 26.⚖️ 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
27. 27.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) ironing the paper (d) letting the paper dry
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
29. 29.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) blue (c) white (d) brown
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the kind of juice
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a balloon (d) lemon juice
34. 34.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
35. 35.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) white paper
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same paper (c) the kind of juice
38. 38.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
39. 39.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
40. 40.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it

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