Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 235 · 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.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
3. 3.⚖️ 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 kind of juice (c) the same paper
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
5. 5.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) letting the paper dry
7. 7.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
9. 9.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
10. 10.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
12. 12.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a balloon
13. 13.🛟 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
14. 14.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) reading the message
15. 15.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) ironing the paper (d) letting the paper dry
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
17. 17.True or false: ironing the paper is a job a child can do. (a) False (b) True
18. 18.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
19. 19.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) putting the iron away (d) plugging in the iron
20. 20.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
21. 21.⚖️ 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
22. 22.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
23. 23.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) white paper (d) yeast
25. 25.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) ironing the paper (d) plugging in the iron
26. 26.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) yeast (d) an adult with an iron
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) lemon juice (d) a cotton bud
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the ironing time
29. 29.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) ironing the paper (d) dipping the cotton bud
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a cotton bud (d) a balloon
31. 31.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
33. 33.⚖️ 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 measure it (c) we change it
34. 34.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
35. 35.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
37. 37.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
38. 38.True or false: cutting the lemon is a job a child can do. (a) False (b) True
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
40. 40.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True

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