Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 490 · 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: white paper is not needed for the secret lemon message. (a) False (b) True
2. 2.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) dark brown words (d) almost nothing
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a balloon (d) a mirror
4. 4.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
5. 5.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) wash your hands (d) rub your eyes
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) lemon juice (d) a mirror
9. 9.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) yeast
11. 11.⚖️ 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
12. 12.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
13. 13.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
14. 14.⚖️ 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
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) the iron setting (d) the same paper
16. 16.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
17. 17.⚖️ 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) True (b) False
18. 18.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
19. 19.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
20. 20.⚖️ 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
21. 21.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) letting the paper dry
22. 22.True or false: reading the message is a job a child can do. (a) True (b) False
23. 23.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
25. 25.True or false: ironing the paper is a job a child can do. (a) False (b) True
26. 26.⚖️ 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) False (b) True
27. 27.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
28. 28.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
29. 29.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
30. 30.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
31. 31.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
32. 32.⚖️ 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
33. 33.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
34. 34.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) putting the iron away
35. 35.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) turmeric powder (d) an adult with an iron
37. 37.⚖️ 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) False (b) True
38. 38.True or false: letting the paper dry is a job for an adult. (a) True (b) False
39. 39.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a mirror (d) a balloon
40. 40.🔮 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

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